Welcome to the board, Poppy.
I don't live in Pittsburgh, but I've been a couple of times. As far as parking at the stadium, I have no idea, but if you're looking for a good place to eat, Grille 36 is Jerome Bettis' restaurant right beside the stadium and it's really good. It's not cheap though.
Another good place that I like is Fat Head's Saloon on Carson Street which isn't quite as expensive, has great sandwiches/burgers, and an awesome selection of microbrewed beers. They also fill growlers if you're into all of that, but it isn't near the stadium and that area should be avoided at night.
Have fun at the game and "Go Steelers"!